<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>字符动画</title>
</head>

<body>
    <video id="video" loop oncanplay="init()" controls src="./asset/鸡你太美.mp4" width="300px" autoplay></video>
    <canvas id="cvs" style="display:none"></canvas>
    <canvas id="cvs2"></canvas>
    <style>
        video,
        canvas {
            position: absolute;
            left: 120px;
            background-color: #fff;
        }
    </style>
    <script>
        var canvas = document.createElement('canvas');
        var context = canvas.getContext('2d');
        const init = () => {
            const ctx = cvs.getContext('2d')
            const ctx2 = cvs2.getContext('2d')
            cvs.height = cvs2.height = video.offsetHeight
            cvs.width = cvs2.width = video.offsetWidth
            const playVideo = () => {
                requestAnimationFrame(playVideo)
                ctx.drawImage(video, 0, 0, video.offsetWidth, video.offsetHeight);
                const { width, height } = cvs
                const data = ctx.getImageData(0, 0, width, height).data
                ctx2.clearRect(0, 0, width, height)
                const bl = 8
                ctx2.font = '12px serif'
                for (let i = 0; i < data.length; i += 4 * bl) {
                    const x = parseInt((i + 1) % (width * 4) / 4)
                    const y = parseInt(i / (width * 4))
                    if (x % bl === 0 && y % bl === 0) {
                        const g = parseInt((data[i] + data[i + 1] + data[i + 2]) / 2)
                        ctx2.fillStyle = `rgba(${g},${g},${g},${data[i + 3]})`
                        ctx2.fillText('6', x, y)
                    }
                }
            }
            playVideo()
        }
    </script>
</body>

</html>